Artificial heart

ABSTRACT

Disclosed herein is a fully implantable artificial heart. The use of flat helical springs to align and reciprocate a bellows structure allows the bellows to pump blood, the multiple solenoids with floating magnetized rods and permanent magnet assemblies held by the flat helical springs provide the power. The artificial heart pumps blood with virtually no friction and no parts to wear out. The use of solenoids advantageously move blood in a gentle, controllable manner.

BACKGROUND Field of the Invention

The invention generally relates in some aspects to an artificial heart,components of an artificial heart, and methods of using the same.

Description of the Related Art

The heart is the muscle that drives the cardiovascular system in livingbeings. Acting as a pump, the heart moves blood throughout the body toprovide oxygen, nutrients, hormones, and to remove waste products. Theblood follows two separate pathways in the human body, the so-calledpulmonary and systemic circulatory circuits. In the pulmonary circuit,the heart pumps blood first to the lungs to release carbon dioxide andbind oxygen, and then back to the heart. Thus, oxygenated blood isconstantly being supplied to the heart. In the systemic circuit, thelonger of the two, the heart pumps oxygenated blood through the rest ofthe body to supply oxygen and remove carbon dioxide, the byproduct ofmetabolic functions carried out throughout the body. The heart suppliesblood to the two circuits with pulses generated by the orderly muscularcontraction of its walls.

In order to keep blood moving through these two separate circulatorycircuits, the human heart has four distinct chambers that work in pairs.As illustrated in FIG. 1, the heart 100 includes a right atrium 120, aright ventricle 140, a left atrium 160, and a left ventricle 180. Onepair of chambers, the right ventricle and left atrium, is connecteddirectly to the pulmonary circuit. In it, de-oxygenated blood from thebody is pumped from the right ventricle 140 to the lungs, where it isoxygenated, and then back to the left atrium 160.

In the systemic circuit, the other pair of chambers pumps the oxygenatedblood through body organs, tissues and bones. The blood moves from theleft atrium 160, where it flows from the lungs, to the left ventricle180, which in turn pumps the blood throughout the body and all the wayback to the right atrium 120. The blood then moves to the rightventricle 140 where the cycle is repeated. In each circuit, the bloodenters the heart through an atrium and leaves the heart through aventricle.

Thus, the ventricles 140, 180 are essentially two separate pumps thatwork together to move the blood through the two circulatory circuits.Four check valves control the flow of blood within the heart and preventflow in the wrong direction. A tricuspid valve 200 controls the bloodflowing from the right atrium 120 into the right ventricle 140.Similarly, a bicuspid valve 220 controls the blood flowing from the leftatrium 160 into the left ventricle 180. Two semilunar valves (pulmonary240 and aortic 260) control the blood flow leaving the heart toward thepulmonary and systemic circuits, respectively. Thus, in each completecycle, the blood is pumped by the right ventricle 140 through thepulmonary semilunar valve 240 to the lungs and back to the left atrium160. The blood then flows through the bicuspid valve 220 to the leftventricle 180, which in turn pumps it through the aortic semilunar valve260 throughout the body and back to the right atrium 120. Finally, theblood flows back to the right ventricle 140 through the tricuspid valve200 and the cycle is repeated.

When the heart muscle squeezes each ventricle, it acts as a pump thatexerts pressure on the blood, thereby pushing it out of the heart andthrough the body. The blood pressure, an indicator of heart function, ismeasured when the heart muscle contracts as well as when it relaxes. Theso-called systolic pressure is the maximum pressure exerted by the bloodon the arterial walls when the left ventricle of the heart contractsforcing blood through the arteries in the systemic circulatory circuit.The so-called diastolic pressure is the lowest pressure on the bloodvessel walls when the left ventricle relaxes and refills with blood. Oneexample of healthy blood pressure is considered to be about 120millimeters of mercury systolic and 80 millimeters of mercury diastolic(usually presented as 120/80).

Inasmuch as the function of the circulatory system is to service thebiological needs of all body tissues (e.g., to transport nutrients tothe tissues, transport waste products away, distribute hormones from onepart of the body to another, and, in general, to maintain an appropriateenvironment for optimal function and survival of tissue cells), the rateat which blood is circulated by the heart is a critical aspect of itsfunction. The heart has a built-in mechanism (the so-calledFrank-Starling mechanism) that allows it to pump automatically whateveramount of blood flows into it. Such cardiac output in a healthy humanbody may vary from about 4 to about 15 liters per minute (LPM),according to the activity being undertaken by the person, at a heartrate that can vary from about 50 to about 180 beats per minute.

Several artificial devices have been developed over the years tosupplement or replace the function of a failing heart in patients. Theseinclude devices developed by companies as well as research institutionssuch as the Berlin Heart Institute, the Pennsylvania State University,the University of Utah, the Cleveland Clinic Foundation, the Universityof Perkinje (in Bruno, Czechoslovakia), the University of Tokyo, theThoratec Corporation, Abiomed Inc., Novacor, and Symbion Inc. Typically,these artificial devices consist of pumps that aim at duplicating therequired pumping functions of the left and right human ventricles. Onemethod of actuation for these pumps has been through the pneumaticaction of an external mechanism. See, for example, U.S. Pat. Nos.4,611,578 and 5,766,207, which are hereby incorporated by reference intheir entireties. Periodic pulses of compressed air drive the pumps atthe desired pressure and rate of cardiac output. A moderate vacuum maybe applied between pulses to allow more rapid refilling of theventricles with blood flowing from the respective atrium.

One notable artificial heart currently in use as an implant for patientswaiting for a heart transplant is the Total Artificial Heartmanufactured by SynCardia Systems, Inc., of Tucson, Ariz. Designed tooperate much the same way as a human heart, this artificial heartreplaces the two active chambers (i.e., the ventricles) of the humanheart with corresponding artificial components. As illustrated in FIG.2, such artificial heart 300 includes two separate chambers orventricles 320 and 340 that replace the right and left ventricles of thehuman heart, respectively. Each chamber is equipped with a respectivediaphragm (360 and 380 in the right and left chamber, respectively) thathas an air contact side and a blood contact side. Each diaphragm isdesigned as a spherical hemisphere. As shown in FIG. 3, the artificialheart 300 is implanted by connecting the top of the right chamber 320 tothe right atrium 120 and the top of the left chamber 340 to the leftatrium 160. The bottom of each chamber is provided with an air line (400and 420 in the right and left chamber, respectively) that is embedded inthe patient's body but extends outside for connection to a pneumaticdriver.

When driven by a supply of pressurized air from the pneumatic driver,each diaphragm 360, 380 discharges blood from the respective chamber320, 340 simulating the function of a ventricle. This phase is referredto in the art as systole or equivalently as the ejection phase. When thepressurized air is removed from the diaphragm, known as diastole or thefilling phase, blood can enter the ventricle from the connected atrium.The rate at which blood enters the ventricle depends on the differencebetween the atrial pressure and the pressure on the air-side of thediaphragm. To increase this filling rate, a slight vacuum of about 10mmHg is normally applied to the air-side of the diaphragm duringdiastole. Artificial valves 144 a (tricuspid), 146 a (bicuspid) and 144b (pulmonary), 146 b (aortic) control the flow from the respectiveatrium into each artificial ventricle and out to the circulatorysystems, respectively.

The pneumatic drivers used to date for driving all artificial heartshave been cumbersome and inadequate for affording patients any degree ofindependent mobility. They employ compressors, vacuum pumps, and airtanks coupled to electrically actuated valves, all of which amounts to alarge and heavy apparatus that can only be transported on wheels andwith considerable effort. Therefore, many attempts have been made duringthe last two decades to produce a portable driver for these devices.However, because of the complexity of the required functionality and thehardware necessary to produce it, pneumatic heart drivers continue to bebulky, require frequent maintenance, and often provide air pulses thatdo not match the performance of the larger drivers they are meant toreplace. Even at the approximate weight of 20 pounds and size of about0.7 cubic feet achieved so far, pneumatic drivers remain unwieldy andsubstantially not portable for a patient who is kept alive by anartificial heart.

In essence, a portable driver needs to be reliable, durable, easy touse, and sufficiently simple in design to be affordable. Unfortunately,each of these requirements contributes to the complexity of the design,which in turn has produced devices that are not sufficiently small andlight-weight to be manageable in the hands of a patient. Furthermore, itis essential that the pneumatic driver be able to provide the correctpressure balance between the left and right ventricles of the artificialheart to ensure the proper operating pressure to the pulmonary andsystemic circuits regardless of the speed of operation. Typically, thisrequires that the driver be able to operate so as maintain, on average,a right atrial pressure of about 9 mmHg, a mean pulmonary arterypressure of about 35 mmHg, a left atrial pressure of about 10 mmHg, anda mean aortic pressure of about 95 mmHg.

This need to provide different operating pressures to the right and leftchambers (ventricles) of the artificial-heart device has not been metheretofore with a simple design suitable for a portable driver. Forexample, the blood pump described in U.S. Pat. No. 4,611,578 includes aconfiguration wherein two reciprocating pistons in a common cylinder maybe operated alternatively to provide redundancy or independently toactuate two separate pneumatically driven blood pumps. This issue is notaddressed in the patent, but it describes a sophisticated control systemthat arguably could be used to provide the correct operating pressure toeach chamber of the artificial heart. However, the complex andmulti-component structure of the device necessarily requires arelatively heavy and large apparatus, though described as portable. Thecommercially available module weighs about 25 pounds and isapproximately 0.6 cubic feet in volume.

U.S. Pat. No. 5,766,207 describes another portable pneumatic driver forventricular assist devices that could also be adapted for an artificialheart. The single pump of the invention could be used to drive bothventricles of an artificial heart, but only at the same pressure andvolume rate. Thus, this device, even if modified to meet the otherrequirements of a portable artificial-heart driver, would not besuitable as an alternative to the stationary modules currently in use.

Therefore, there remains a strong need for an improved artificial heartthat could serve as a permanent cardiac replacement. Preferably, theartificial heart and all of its associated components are completelyimplantable.

SUMMARY

Embodiments of artificial hearts as disclosed herein can have severalpotential advantages. The use of flat helical springs to align a bellowsstructure allows the structure to flex its size to pump blood, themultiple solenoids with floating magnetized rods and permanent magnetassemblies held by the flat helical springs provide the power; theartificial heart pumps blood with virtually no friction and no parts towear out. The use of solenoids advantageously move blood in a gentlemanner. The solenoids are controlled by the digital circuitry. Thecontraction force, release force, duration between forces, the rate ofchange of forces are all controlled by a microprocessor for optimumoperation. This microprocessor program also minimizes energyconsumption. By use of the multi-turn flat helical springs, the movementof each solenoid step is small and preset; this optimizes the force andefficiency of solenoid operation. The size and shape of the solenoid rodattached to the permanent magnet can be used to control and balance thesolenoid power requirements between attracting and repelling thepermanent magnet. The initial solenoid motion (e.g., linear distancemoved between the solenoid and the spring magnet) and the endingsolenoid motion are twice or at least twice the motion of theintervening solenoids; this is to ensure there is no accidental lock upof the solenoids. Use of a floating solenoid rod allows in someembodiments more contracting distance than would a solid rod. Solenoiddrives can use regulated current pulsed operation in a low duty cycle.This drive system can provide extensive power if needed, up to 3 or 4times or more the minimum drive power. Space is shared between atria andventricles allowing for maximum flexibility and cardiac output; whilethe total atrioventricular volume is fixed, the range of ratios ofatrial volume capacity to ventricular volume capacity can vary widely.Movement of the bicuspid valve and the mitral valve with designs asdisclosed herein minimize blood movement (nearly all blood movement isaxial), and provides little chance for damage to the blood cells. Motionof the blood within the artificial heart includes squeezing out orpulling in just like the biological heart, with normal space between thecells. There is no pinching of the blood cells which might cause damage.The arrangement of the flat helical springs, solenoid rod and solenoidis unique, and described in detail herein.

Further advantages of certain embodiments of artificial hearts asdisclosed herein include incremental power operation. The arrangement ofthe permanent magnet locks can save energy. Also, the spring forceconstant of the flat helical springs enables the even distribution offorce for every solenoid operation in the pump. Linear springs arepreferred in some embodiments, but non-linear springs (e.g., a pair ofnon-linear springs) can also be utilized. Furthermore, the use ofbellows between the atrial and ventricles, atria, ventricles, and asradial outer walls for the blood flow chamber, as well as solenoids tocontrol the flow of blood by a programmed processor in digitalincrements offers virtually no friction, gentle operation and longoperating life. Moreover, the use of bellows removes any sharp changesin pressure, and provides a good buffer for blood pressure transientsminimizing their magnitude and duration. Also, large atriums allowconstant inflow of blood. The use of cylindrical ventricles allowssmooth, steady programmed pressure controlled output. The use of workedmetal allows long life by minimizing fatigue stress effects. The use ofincremental control and incremental feedback allows precision operation.The use of multiple turn flat helical springs permits the bending actionto be small thus minimizing stresses while providing adequateincremental stroke length to contribute to the total volume of bloodbeing pumped in each heart beat cycle. This artificial heart system hasmany back-up features so that any failure modes can be repaired and/orcompensated for by the digital control circuitry.

In some embodiments, solenoids can be operated in push-pull mode, one ata time, independently or as a group or at the same time, depending onthe program. These features speed up solenoid operation and allow veryflexible programming.

In some embodiments, disclosed is an artificial heart that includes anouter housing defining a first chamber having a fixed volume. Thechamber can include a right ventricle and a left ventricle separated bya single movable plate structure within the fixed volume. The movableplate structure can be coupled to the center of a magnet and configuredto vary a right ventricular volume and a left ventricular volumeinversely proportionally to each other upon movement of the movableplate structure. The artificial heart can also include a first springassembly, and a second spring assembly operably connected to the magnetand the movable plate structure. The artificial heart can also include afirst drive coil operably connected to a first end of the chamber and asecond drive coil operably connected to a second end of the chamber. Thefirst drive coil and the second drive coil can be configured to attractor repel the magnet, thereby moving the movable plate structure. In someembodiments, the first spring assembly and the second spring assemblycan include a bellows spring operably connected to a helical spring. Thefirst spring assembly and the second spring assembly can be configuredto store energy and actuate the movable plate structure. The relativecontribution to movement of the movable plate structure by the firstspring assembly and the second spring assembly can increase when therelative contribution of the first drive coil and the second drive coilto the movable plate structure decreases. The movable plate structurecan be configured to have a frictionless, noncontact predetermined firststop location when a magnetic contraction force from the magnet is inequilibrium with the force from the first spring assembly and the firstdrive coil. The movable plate structure can be configured to have africtionless, noncontact predetermined second stop location when a forcefrom the second spring assembly is in equilibrium with the force fromthe magnetic contraction force in the opposite of the first stopposition. The first drive coil can drive a control. The artificial heartcan also include a second chamber that includes a left atrium and athird chamber that includes a right atrium. The left atrium and theright atrium can be fluidly connectable to the first chamber, the secondchamber and the third chamber and configured to receive continuous bloodflow, as well as have a preset pressure controlled profile. The leftatrium and the right atrium can be configured such that blood flowthrough the left atrium and the right atrium can flow into the leftventricle and right ventricle respectively allowing mechanical actuationof the magnet by the blood flow.

In some embodiments, there are no wires within the fixed volume,preventing loose connections or cables within the fixed volume. In someembodiments, the artificial heart can further include an aortic valveconfigured to be connected to a patient's aorta, and a pulmonic valveconfigured to be connected to a patient's pulmonary artery. In someembodiments, the aortic valve cross-sectional area is large and about orat least about 5%, 10%, 15%, 20%, or more of the cross-sectional area ofthe first chamber. In some embodiments, the magnet is a high coercivity,high flux density magnet, such as, for example, a neodymium iron boronmagnet.

Also disclosed herein is an artificial heart that can include an outerhousing. The outer housing can include a right heart valve plate and aleft heart valve plate spaced axially apart by a first bellows springand a second bellows spring. The artificial heart can also include asolenoid connected to a first drive coil and a second drive coil. Thefirst drive coil can be operably connected to the right heart valveplate and the second drive coil operably connected to the left heartvalve plate. The artificial heart can also include a magnet operablyconnected to a plate structure spaced axially between the first drivecoil and the second drive coil. The magnet can be operably connected toa first end of the first bellows spring and a first end of the secondbellows spring. The magnet can be configured to move axially uponactivation of the first drive coil and the second drive coil resultingin conversion of electrical energy to mechanical energy, thereby axiallyelongating one of the first bellows spring and the second bellows springand simultaneously contracting the other of the first bellows spring andthe second bellows spring resulting in the release of energy, movingblood in or out of the heart by movement of the plate structure. Theartificial heart can also include at least one sensor configured todetermine at least one of the position, velocity, and direction oftravel of the magnet. The artificial heart can also include aservomechanism controller configured to receive data from the sensor andcontrol power to the first drive coil and the second drive coil, therebyactuating the magnet and the plate structure. The servomechanismcontroller can be configured to provide precise control of the positionand speed of the magnet, such as at all times. The solenoid can beconfigured to actuate the magnet during periods of relative efficiency.The artificial heart can be made of an appropriate material, such asbiocompatible titanium for example. Axial movement of the magnet in acranial direction can increase a volume capacity of ventricles of theheart by a first amount while decreasing a volume capacity of the atriaby the same first amount. The outer housing can be rigid. The controllercan include a high gain, phase lock digital servomechanism feedbacksystem. The controller can also be configured such that the platestructure is in very close proximity to, but never physically touchesthe left heart valve plate or the right heart valve plate during normaloperation, thus acting as a virtually frictionless pump and increasingoperating life. The controller can also be configured such that platestructure is separated by a minimum of about 0.1 mm with respect to theleft heart valve plate or the right heart valve plate during normaloperation. The artificial heart can also include discrete left and rightatrial chambers with controlled pressure and range of operation, whichcan be axially movable plates. Any or all of the chambers can berelatively large, and be configured to reduce restrictions on bloodflow, as well as configured to control pressure and range of operation.The artificial heart can also be configured such that blood flow throughthe artificial heart directly cools the first solenoid and the secondsolenoid. The artificial heart can also include one, two, or moresensors, configured to determine at least one of blood pressure, bloodoxygen level, and blood temperature. The controller can be configured toreceive data regarding at least one of blood pressure, blood oxygenlevel, and blood temperature, analyze the data, and adjust power to thefirst drive coil and the second drive coil accordingly. The artificialheart can include, or have an outer housing that is a rigid structure.Each of the drive coils, heart valve plates, sensors, and sensor wirescan be mounted to the artificial heart. The artificial heart may notinclude any loose wires or sensors. The artificial heart can beconfigured to minimize force on the parts when the artificial heart isbeating.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a representation of the human heart.

FIG. 2 is a schematic view of a prior art artificial heart.

FIG. 3 is a representation of the artificial heart of FIG. 2 connectedto the cardiac atria of a human body.

FIG. 3A is a schematic view of the fully implantable heart of thepresent invention.

FIG. 4A illustrates a schematic side view of one embodiment of anartificial heart having a single spring.

FIG. 4B is a cross-sectional view through line B-B of FIG. 4A lookingfrom a generally cranial to a generally caudal direction.

FIGS. 4C-4E illustrate views of another embodiment of an artificialheart with large discrete atria.

FIG. 5 is a two-dimensional schematic incline plane representation ofthe actual three-dimensional helical spring and solenoid ring.

FIG. 6A is a schematic side view of the helical spring as previouslydescribed in a fully uncompressed configuration.

FIG. 6B illustrates the spring of FIG. 6A in a fully compressedconfiguration.

FIG. 6C is a top view illustrating a plurality of solenoids 1A-16Awithin solenoid ring.

FIGS. 7A-7B illustrate another embodiment of an artificial heart havinga plurality of springs.

FIG. 8 is a two-dimensional schematic incline plane representation ofthe actual three-dimensional helical springs and solenoid ring.

FIG. 9A is a schematic side view of the helical springs forming a doublehelix.

FIG. 9B illustrates the springs of FIG. 9A in a fully compressedconfiguration.

FIG. 9C is a top plan view of the helical spring of FIG. 9A.

FIG. 10A-10B schematically illustrate a close-up detail view of ahelical spring according to some embodiments of the invention.

FIG. 11 illustrates several consecutive segments of the non-linearspring illustrated in FIGS. 10A-10B.

FIGS. 12A and 12B illustrate a top view and side view, respectively of anon-linear helical spring 13 as previously described, with coupledmagnetic rods.

FIG. 13 illustrates more details of the manner in which the solenoidattracts the magnet of the spring.

FIGS. 14A-14D illustrate another embodiment of an artificial heart, withspring assemblies positioned near both the cranial and caudal ends ofthe artificial heart, and the solenoid assembly is positionedlongitudinally therebetween.

FIGS. 15-16 is a two-dimensional schematic incline plane representationof the actual three-dimensional atrial helical springs and ventricularhelical springs and solenoid ring.

FIG. 17 illustrates more details of a “push-pull” solenoid assemblysimilar to that of FIG. 13, with features as described in connectionwith FIGS. 14A-16 above.

FIGS. 18-18B illustrates schematically an embodiment of a compactartificial heart having an axially movable central magnet.

FIG. 18AA illustrates a laser position sensor module, according to someembodiments of the invention.

FIG. 19-19G illustrates schematically operation of the artificial heartof FIG. 18 with a moving magnet at various positions of operation.

FIG. 19H illustrates a graphical relationship of magnet position withrespect to the forces on the magnet, in accordance with someembodiments.

FIG. 19I illustrates an embodiment of functionality of a multi-channellocation, direction, and speed sensor configured to be in operativecommunication with a controller.

FIG. 20 illustrates a graphical relationship of solenoid force (inNewtons) on the Y axis with respect to stroke distance (measured inmillimeters).

DETAILED DESCRIPTION

Disclosed herein is an artificial heart designed to be implanted in thehuman or other animal body and offers long operating life. The heartrequires only occasional external electromagnetic connection exterior tothe body to recharge an internal battery also implanted in the body. Theuse of flat helical linear or non-linear springs in some embodimentsprovides lateral stability, providing a type of alignment spine to themoving parts of the heart, primarily the heart chambers' inner and outerbellows which are held in place, top and bottom, by the flat circularplates at top and bottom of the artificial heart. These top and bottomplates are also secured to a solid housing, e.g., a cylinder, made ofmetal in some embodiments, completing the enclosure of the heart. Thelateral stability of the moving springs assures freedom from slidingfriction between the springs and both sets of bellows. Solenoids withpermanent magnetic rod assemblies held by the flat helical springsprovide the power for the artificial heart to pump blood with no slidingfriction and no parts to wear out. Implantable units can be enclosed inone, two, or more biocompatible materials, such as a metal well known tobe tolerated by the human body. Types of metals contemplated for use incertain embodiments as disclosed herein include but are not limited tosteel (e.g., stainless steel), tungsten, titanium, and platinum. Otherpossible metals could include, for example, tantalum, gold, palladium,silver, nickel, cobalt, copper, or chromium. The metals can be alloys,such as Nitinol or Elgiloy, and can be combinations of metals. Othertype of materials include a biocompatible polymer such as ePTFE or PTFEfor example.

The heart is designed for long life and low energy consumption.Operation of the artificial heart operation is similar to that of thenative heart. It has four chambers, and four valves that may be, forexample, a ball-type, tilting-disc, bileaflet, trileaflet, or biologicalvalve. The valves could be mechanically activated, electronicallyactivated, or a combination of the above. The artificial heart pulls inblood and ejects blood, and can be programmed by bio-feedback signalswhich direct digital circuitry to provide precise control of eachsolenoid as the blood moves into the atria, then the ventricles andfinally exits to the body's arteries. In this process blood flow isgentle and virtually completely axially flowing, minimizing any radialand turbulent motion and pinching of the blood cells, that could causeundesired hemolysis or clotting. The biofeedback control system can beset up immediately after implantation. After implantation, modificationsto the control system parameters can be made externally to adapt thesystem to changing needs of individual patients. Such external changesaugment the constant internal biofeedback system used to controlindividual current pulses applied to each solenoid.

FIG. 3A illustrates schematically certain components of an artificialheart system 50 with respect to a patient 1000, according to someembodiments of the invention. While shown as discrete modules, it willbe appreciated that various modules can be integrated together orseparated according to the desired clinical result. In some embodiments,an artificial heart system 50 includes an external power supply 99. Thiscan be in some cases a relatively large power supply which patients canuse at home or at work while resting and sleeping. It can also be builtmore compactly as, for example, a belt with 8 hours or more of batteryenergy. The artificial heart system can also include a wireless energy(e.g., induction) transfer system 98. In some embodiments, this systemincludes a plurality of coils (e.g., 2 coils), one internal and oneexternal which transfer energy via magnetic field through the skinwithout physically piercing it. The internal coil receives the energysending it to the rectifier and regulator in the internal batteryenclosure. Fairly high frequency can be used to minimize size, such as,for example, between about 300 kHz to 3000 kHz, between about 500 kHz toabout 2000 kHz, or at least about 1000 kHz, 2000 kHz, 3000 kHz, 4000kHz, 5000 kHz or more, however, any suitable frequency can be utilizeddepending on the desired result.

The system can include an internal power source 97, such as arechargeable battery and a regulator. In some embodiments, the systemprovides over about or at least about one, two, three, four, or morehours of battery life in normal use, although other battery capacitiesare also possible. The regulator can provides fast battery charging,such as about three hours or less in certain cases. An internal controlunit 96 contains a microprocessor programmed to control the heart motioncontrol electronics. This hardware and/or software controller includes atransceiver used to control externally heart operations as well as totransmit heart status signals including, for example, diastolic andsystolic pressure waveforms, oxygen content of the blood waveform, heartrate waveform and battery condition.

Complete heart condition is available at a glance when interrogated,such as via an external device 1002 which may be a computer, tablet,mobile phone, PDA, database, electronic health records system, or thelike that are configured to receive such data from the internal controlunit 96. In various embodiments, the internal control unit 96 maycommunicate wirelessly with an external device 1002 via a protocol suchas 802.11x, WiFi, Bluetooth, Zigbee, and/or via cellular networks.

In some embodiments, the internal control unit 96 is in operativecommunication with various biosensors or probes, for example, sensorsthat can detect pH, pCO₂, pO₂, pressure, and temperature. Cardiac output(CO) can be calculated by combining two pO2 measurements obtained from apair of probes, one disposed in an artery and the other in a vein.Alternatively, or in addition to the aforementioned sensors, sensors forother blood parameters such as potassium, sodium, calcium, bicarbonate,urea nitrogen, creatinine, bilirubin, hemoglobin, glucose, and lactatecan also be in operative communication with the internal control unit96. Some biosensors or probes that can be used in connection withembodiments herein are described, for example, in U.S. Pat. Pub. No.2010/0057046 to Stevens et al. which is hereby incorporated by referencein its entirety.

The sensors placed in the heart in continuous high-speed high-resolutiondigital form closely monitor the operation of the heart. The systolicpressure and diastolic pressure can be measured as each solenoid closesor opens. A small change in any solenoid operation could be detected.Thus, problems can be detected as they happen. The oxygen content of theblood can also be measured in every heartbeat. This can measure theeffectiveness of the body to assimilate the oxygenated blood beingpumped and control the heart rate. No power will be wasted by over orunder driving the heart. The power drive to the solenoids has more than3 to 4 times the force required to drive the solenoids thus full controlof the solenoids is achieved. The solenoids in the helical spring(s) canbe operated independently to correct problems. Power can be increased ordecreased accordingly for the needs of each solenoid. The controlprogram can be instantaneously changed with remote sensors to vary theoxygen level or blood pressure level as needed. In some embodiments, asystem includes a biofeedback loop can also include interpreting thephysiologic parameter feedback information; and adjusting a setting suchas heart rate or contractility of the artificial heart 50 at leastpartially based on the physiologic parameter feedback information. Insome embodiments, one, two, or more biosensors can detect sympatheticnervous system activity in the brain, spinal cord, or circulating levelsof catecholamines such as epinephrine and norepinephrine;parasympathetic nervous system activity such as vagus nerve tone;carotid sinus, aortic arch, and other baroreceptor activity; kineticactivity such as increased extremity movement; ATP production;mitochondrial activity; or other cellular activity sensors; and sendsignals to the internal control unit 96 which could be configured toincrease or decrease heart rate and/or contractility of the artificialheart 50, for example, accordingly. In one embodiment, a sensormeasuring a drop in blood pressure or peripheral vascular resistancewould send signals to the internal control unit 96, which could sendsignals to the artificial heart to increase heart rate and/orcontractility.

The internal battery is also closely monitored. The charge rate anddischarge rate and voltage variation between them allows prediction ofthe battery life, and energy remaining in the battery. The battery canbe recharged or replaced before complete discharge or failure.

The artificial heart mechanism contains the solenoids, spring andpermanent magnet pumping mechanism, as discussed further herein. Theartificial heart, as disclosed herein can be a permanent replacement fora failing heart, such as congestive heart failure due to ischemic,dilated, restrictive, or other cardiomyopathies. It operates quitesimilarly to a biological human heart. An artificial heart can have fourchambers and four valves, and lack any pistons in some embodiments. Theartificial heart contracts and ejects the blood for distribution to therest of the body just like the human heart, causing minimal to no damageto circulating blood cells, and may or may not require the use ofanticoagulant therapy. The artificial heart is designed to operate foryears, and up or exceeding the natural life of a patient, unlikeconventional artificial hearts which are generally intended to betemporarily placed as a bridge to a heart transplant. It can beprogrammed for changing needs as the patient's requirements change. Ithas low power consumption allowing the patient long operating periodswithout an external battery, using only the internal battery, offeringoperating intervals measured in hours rather than minutes.

Several modes of operation are possible, depending on the desiredclinical result. FIG. 4A illustrates a schematic side view of oneembodiment of an artificial heart 50. The artificial heart includes anouter housing 5 that may take the form of a cylinder, although otherellipsoid, spherical, cubical, or other geometric configurations arealso possible. Outer housing 5 includes one or more sidewalls 51, aswell as top plate 3 and bottom plate 19. Top plate 3 can includeapertures to allow for blood flow into the artificial heart 50 via thesuperior vena cava 1, inferior vena cava, and pulmonary vein 2. Bottomplate 19 can include apertures for blood flow out of the artificialheart 50 via the aorta 60 and the pulmonary artery 61. In someembodiments, the sidewall 51, top plate 3, and bottom plate 19 are rigidor relatively rigid structures.

In some embodiments, the outer housing 5 of the artificial heart has amaximal longitudinal dimension of between about 3″ and about 7″ inlongitudinal dimension, or no more than about 6″, 5.5″, 5″, 4.5″, 4″,3.5″, 3″ or less inches in longitudinal dimension; a maximal transversedimension of between about 2″ and about 5″, or no more than about 6″,5.5″, 5″, 4.5″, 4″, 3.5″, 3″ or less in transverse dimension; andbetween about 1.5″ and about 3.5″ in thickness, or no more than about5″, 4.5″, 4″, 3.5″, 3″, 2.5″, 2″, or less in thickness.

With respect to the right-sided circulation of the patient, deoxygenatedblood from the body including the legs, arms, head, and torso enters theartificial right atrium 6 of the artificial heart 50 via either thesuperior vena cava 1 or the inferior vena cava (not shown). Thedeoxygenated blood then travels through the tricuspid valve 8 into theright ventricle 15, through the pulmonic valve 17 and out into thepulmonary artery 61, where the blood can then be reoxygenated in thelungs. With respect to the left-sided circulation of the patient,reoxygenated blood from the lungs enters the left atrium 7 via thepulmonary vein 2. The reoxygenated blood then travels through the mitralvalve 9 into the left ventricle 16, through the aortic valve 18, and outthe aorta 60, to perfuse the rest of the body. Blood inflows into theatria 6, 7 are facilitated by a pressure gradient caused by movement ofthe axially movable plate 10 in a generally caudal direction.

Axially movable plate 10 houses the mitral valve 9 and the tricuspidvalve 8 therethrough. Axially movable plate 10 is operably attached,such as on its caudal surface at attachment point 11, to a first end ofa helical spring 13. While the embodiment illustrated shows only asingle helical spring 13, other embodiments described elsewhere hereindescribe a plurality of springs, such as 2, 3, 4, or more springs.Spring 13 is operably attached to a plurality of magnets 12 at variousregularly or irregularly spaced apart locations along the length of thespring 13.

Within the artificial heart 50, an atrial septal wall 21 separates theleft atrium 7 from the right atrium 6, while a ventricular septal wall24 separates the left ventricle 16 from the right ventricle 15. Outeratrial wall 21 separates the atria 6, 7 from an outer chamber 4 betweenthe atria 6, 7 and the outer sidewall 51 of the artificial heart 50.Outer ventricular wall 23 separates the ventricles 15, 16 from a workingspace 4 between the ventricles 15, 16 and the outer sidewall 51 of theartificial heart 50. Walls 21, 22, 23, and 24 in some embodiments aremade of a flexible biocompatible material to form bellows structures.The bellows structure may be made, for example, of a polymer such asPTFE or ePTFE, or a metallic material such as titanium or Nitinol.Housed within the outer chamber 4 is a solenoid ring 14, which isoperably attached at attachment point 20 to a second end of the helicalspring 13. Solenoid ring 14 could be circular or ovoid in shape in someembodiments, although non-arcuate shapes such as a square, rectangle,and the like could also be utilized.

FIG. 4B is a cross-sectional view through line B-B of FIG. 4A lookingfrom a first, e.g. generally cranial to a second, e.g. generally caudaldirection. The solenoid ring 14 (housed radially in between sidewall 51of outer housing 50 and outer ventricular wall 23) contains a pluralityof solenoids, such as 16 solenoids as shown. However, other embodimentscould include, for example, between about 2-64 solenoids, 4-32solenoids, or 8-24 solenoids for example. These solenoids are marked 1Athrough 16A as illustrated, and the consecutively numbered solenoids,e.g., 1A and 2A, are spaced about 67.5 degrees apart, with adjacentsolenoids spaced about 22.5 degrees apart along the circumference of thesolenoid ring 14, although a number of other regular and irregularspacings are also envisioned. As noted previously, the helical spring 13is connected to the moveable plate 10 at position 11 and to the solenoidring assembly 14 at position 20.

FIG. 4C illustrates a portion of an artificial heart 700 similar to theartificial heart described and illustrated in connected with FIGS.4A-4B, but also including two discrete, relatively large atria: rightatrium 719 and left atrium 720, of which blood can enter via respectiveright atrial entry portal 701 and left atrial entry portal 702. Theatria 719, 720 can be configured to be independently controlled. Theright atrial pressure can be controlled by the action of opposinghelical springs 713, 717. The left atrial pressure can be presetcontrolled by the action of opposing helical springs 723, 725. The sizeof the atria can vary and be defined by right atrial moving plate 715and left atrial moving plate 722, which serve to move blood intorespective right ventricle 705 and left ventricle 714. The right atriumcan also include bellows 712, 718; the left atrium similarly includesbellows 721, 726. Also illustrated (and described in connection withother embodiments herein) are pulmonary valve 704, right ventricle 705,solenoids 706 (any number, such as 16 solenoids as described elsewhereherein), tricuspid valve 707, left ventricular bellows 708, aortic valve709, left ventricle moving plate 710, mitral valve 724, and rightventricular bellows 727. Also shown is solenoid ring assembly 710, whichalong with the bellows and helical springs can be configured for purelyaxial movements, to hold the system together, and prevent parts fromsliding against each other, resulting in a long operating life for theartificial heart 700.

FIG. 4D is a top view at the level of line A-A of FIG. 4C. Illustratedschematically are right atrial entry portal 701 and left atrial entryportal 702, and artificial heart housing 703. FIG. 4E is across-sectional view through line B-B of FIG. 4C. Illustratedschematically are right ventricular bellow 727, right ventricle 705,left ventricular bellow 708, left ventricle 714, pulmonary valve 704,aortic valve 709, solenoid ring assembly 710, and solenoids 706.

FIG. 5 is a two-dimensional schematic incline plane representation ofthe actual three-dimensional helical spring 13 and solenoid ring 14 aspreviously illustrated and described. As noted previously, cranial endof the spring is attached to axially movable plate 10 at attachmentpoint 11, while the caudal end of the spring 13 is attached to thesolenoid ring plate 14 at attachment point 20. The spring 13 is operablyconnected to a plurality of magnets (e.g., magnet rods 12) spaced apartalong the length of the spring, each magnet 12 corresponding to aparticular solenoid 1A-16A, such as in a 1:1 ratio of magnets 12 tosolenoids 1A-16A. As the solenoids 1A-16A are energized one by one in apredetermined series, each solenoid will magnetically attract acorresponding magnet rod 12, and as such the spring 13 is forcedprogressively in a caudal direction along with the axially movable plate10, causing blood to flow out of the ventricles 15, 16 during systole.For example, when solenoid 1A is energized, the solenoid 1A will pull acorresponding magnet rod 12 in a second, e.g. caudal direction such thatthe magnet rod 12 locks on the solenoid 1A. This incremental motionmoves the entire spring structure 13 stepwise in a caudal direction. Thepower is then removed from solenoid 1A while, at the same time, solenoid1A comprises a complementary permanent magnet that has an attractiveforce on the magnet rod 12 that is sufficiently strong to hold the rod12 in place in the solenoid 1A after power is removed from the solenoid.Power is next applied to solenoid 2A, the time interval (either regularor irregular) between the applied power pulses and the amount of powerapplied is set by the digital control program to minimize powerconsumption and to provide the required blood pressure. In someembodiments, the total time to activate all solenoids such that thespring 13 moves from a fully expanded configuration to a fullycompressed configuration is between about 50 msec to about 1,000 msec,such as between about 100 msec and about 800 msec. This sequence willcontinue until all solenoid rods and coils are locked together. Thedistance between the movable plate 10 and solenoid ring 14 closes stepby step in a balanced fashion as each solenoid locks to its permanentmagnet. Blood is ejected out of the right ventricle 15 and leftventricle 16 via pulmonic valve 17 and aortic valve 18 respectively. Insome embodiments, the maximum axial distance that the movable plate 10can travel is between about 2 inches and about 6 inches, or betweenabout 3 inches and 5 inches. In some embodiments, the movable plate 10can travel axially up to 50%, 60%, 70%, 80%, 85%, 90%, 95%, or more ofthe maximal longitudinal dimension of the artificial heart 50.

After a brief and predetermined interval, the blood from ventricles 15,16 having been ejected into the pulmonary artery 61 or aorta 60 andretrograde flow being checked by the pulmonic 17 and aortic 18 valvesrespectively, the solenoids 1A-16A will begin to remove their magnetichold on its corresponding rod 12. This is done by applying power to thesolenoid 1A-16A in the reverse sequence and direction as when attractingthe magnetic rod 12 to the respective solenoids 1A-16A. This isaccomplished by applying a current pulse to solenoid e.g., 16A, ofopposite polarity and to the remaining solenoids, stepwise and inreverse order. As each solenoid 1A-16A releases its lock oncorresponding magnet 12 it pushes the plate 10 in a first, e.g., cranialdirection step by step, in a balanced fashion. The spring force andsystolic pressure force maintain the plate 10 in a cranial orientationduring diastole. By balanced is meant to energize the solenoids notnecessarily in numerical sequence (although numerical sequenceenergization is possible) but by energizing every fourth solenoid in anembodiment having 16 solenoids (although other predetermined sequences,such as adjacent solenoids, or every second, third, fifth, sixth,eighth, etc. solenoid could be energized depending on the desiredclinical result) and then returning to advance one more and thenenergize succeeding fourth solenoids etc. until all 16 solenoids havebeen energized.

When the axially movable plate 10 moves in a cranial direction, thepressure in the ventricles 15, 16 is reduced, the tricuspid valve 8 andmitral valve 9 will open and allow in the blood flows from atria 6, 7into ventricles 15 and 16 respectively. It should be noted that theblood is almost continuously flowing into the atria. The variable atrialvolume capacity advantageously provided by axially movable plate 10allows an extra buffer allowing for continuous blood flows into theatria 6, 7.

After the moveable plate 10 moves to its maximum extent in a cranialdirection and spring 13 is in an unstressed, uncompressed configuration,the artificial heart 50 is ready to begin its next heart beat cycle. Useof the terms up and down, or superior and inferior herein refers to thenormal position of the heart in an upright patient, while cranial(toward the patient's brain) and caudal (toward the patient's feet)account for orientation of the heart with the patient in other positionsas well. However the heart 50 will generally operate properly inpositions other than upright since gravitational forces are smallcompared to the solenoid initiated forces.

FIG. 6A is a schematic side view of the helical spring 13 as previouslydescribed in a fully uncompressed configuration, having longitudinaldimension X2. Not all magnetic rods 12 are illustrated for simplicity.FIG. 6B illustrates the spring 13 of FIG. 6A in a fully compressedconfiguration, with magnetic rods 12 locked down to their respectivesolenoids 14, and the spring 13 having longitudinal direction X1. Insome embodiments, uncompressed dimension X2 is at least about 2×, 3×,4×, 5×, 6×, 7×, 8×, 10×, or more with respect to the compresseddimension X1. FIG. 6C is a top view illustrating a plurality ofsolenoids 1A-16A within solenoid ring 14.

FIGS. 7A-7B illustrate another embodiment of an artificial heart 70.Artificial heart 70 is similar to artificial heart 50 having variouscomponents as illustrated in FIGS. 4A-4B, one difference being thatinstead of only having a single spring 13, a plurality of springs 13, 26are utilized, which can be flat helical springs forming a double helixpattern, the first spring 13 and the second spring 26 in someembodiments sharing a common longitudinal axis, and differing by atranslation along the axis. A first spring 13 is operably attached atits cranial end to axially movable plate 10 at attachment point 11, andoperably attached at its caudal end to solenoid ring assembly 14 atattachment point 20. Similarly, a second spring 26 is operably attachedat its cranial end to movable plate at attachment point 25, and operablyattached at its caudal end to solenoid ring assembly 14 at attachmentpoint 27.

FIG. 7B is a cross-sectional view through line B-B of FIG. 7A lookingfrom a generally cranial to a generally caudal direction. The solenoidring 14 contains a plurality of solenoids labeled 1A-8A and 1B-8B, suchas 16 solenoids as shown or another desired number as previouslydisclosed.

FIG. 8 is a two-dimensional schematic incline plane representation ofthe actual three-dimensional helical springs 13, 26 and solenoid ring 14as previously illustrated and described. As noted previously, cranialend of the first spring 13 is attached to axially movable plate 10 atattachment point 11, while the caudal end of the first spring 13 isattached to the solenoid ring plate 14 at attachment point 20. Cranialend of the second spring 26 is attached to axially movable plate 10 antattachment point 25, while the caudal end of the second spring 26 isattached to the solenoid ring plate 14 at attachment point 27. Eachspring 13, 26 is operably connected to a plurality of magnets (e.g.,magnet rods 12 connected to first spring 13, and magnet rods 12′connected to second spring 26) spaced apart along the length of thesprings 13, 26, each magnet 12, 12′ corresponding to a particularsolenoid 1A-8A or 1B-8B respectively, such as in a 1:1 ratio. In theaforementioned embodiment with 16 magnets and 16 solenoids, first spring13 is connected to 8 magnets while second spring 26 is also connected to8 magnets, although the first spring 13 could also have more or lessmagnets than the second spring 26 depending on the desired clinicalresult.

In some embodiments as illustrated, a plurality of solenoids can beenergized simultaneously. When solenoids A1 and B1 are energized at thesame time, the coil A1 will pull the permanent magnet rod 12A1 in acaudal direction locking on the solenoid A1 and solenoid B1 will pullthe magnet rod 12B1 in a caudal direction to lock on the solenoid B1.This incremental movement moves the entire spring structure 13 andspring structure 26 at same time and same distance. The power is thenremoved from the solenoid coils A1 and B1. The permanent magnet'sattractive force on the rod is sufficiently strong to hold the rods inplace on the solenoid after power is removed from the solenoids. Poweris next applied to solenoids A2 and B2 to attract magnets 12A2 and 12B2respectively, the time interval between the applied power pulses and theamount of power applied is set by the digital control program tominimize power consumption and to provide the required blood pressure.This sequence will continue until all magnetic rods 12 and solenoidcoils A1-A8 and B1-B8 are locked together. The distance between themoving plate 10 and solenoid ring 14 closes step by step in a balancedfashion as previously described as each solenoid locks to itscomplementary permanent magnet. Blood is ejected out of the rightventricle 15 and left ventricle 16 via pulmonic valve 17 and aorticvalve 18 respectively.

After a brief and predetermined interval, the blood from ventricles 15,16 having been ejected into the pulmonary artery 61 or aorta 60 andretrograde flow being checked by the pulmonic 17 and aortic 18 valvesrespectively, each solenoid A1-A8 and B1-B8 will start to remove itshold on its corresponding rod 12. This can be accomplished by applying acurrent pulse, e.g., simultaneously to solenoid pairs B8 and A8, ofopposite polarity and to the remaining solenoid pairs, stepwise and inreverse order. As each solenoid pair releases its lock on correspondingmagnet 12 it pushes the plate 10 cranially step by step, in a balancedfashion. The spring force and systolic pressure force maintain the plate10 in a cranial orientation during diastole.

FIG. 9A is a schematic side view of the helical springs 13, 26 forming adouble helix as previously described in a fully uncompressedconfiguration, having longitudinal dimension X2. Not all magnetic rods12 or 12′ are illustrated for simplicity. FIG. 9B illustrates thesprings 13, 26 of FIG. 9A in a fully compressed configuration, withmagnetic rods 12, 12′ locked down to their respective solenoids 14, andthe spring 13 having longitudinal direction X1. In some embodiments,uncompressed dimension X2 is at least about 2×, 3×, 4×, 5×, 6×, 7×, 8×,10×, or more with respect to the compressed dimension X1. FIG. 9C is atop view illustrating a plurality of solenoids A1-A8 and B1-B8 withinsolenoid ring 14.

FIG. 10A-10B schematically illustrate a close-up view of a helicalspring 13 according to some embodiments of the invention. Asillustrated, the spring 13 can have a first thicker portion 80 and asecond thinner portion 81, portions 80, 81 made out of two distinctpieces of either the same or a different material, such as a metal or apolymer for example. The first thicker portion 80 could have a thicknessin some embodiments that is at least 1.5×, 2×, 3×, 4×, 5×, 6×, 7×, 8×,9×, 10×, 12×, 15×, as thick as the second thinner portion 81. The spring13 can be divided into a number of segments 84, 85 divided at part line82, such as 16 segments in some cases. The spring segments are formedfrom the thicker 80 of the two pieces of material using, for example,laser cutting, leaving negligible kerf removal. The spring 13 can alsoinclude a cavity 83, such as a “quarter circle” cavity removed fromtheir upper corners, leaving only the thinner portion 81 to bend anddeflect at joint 86. After attachment to the thin member 81 of thenon-linear spring assembly 13, these quarter round cavities 83 nowappear to be semicircles with the remaining thickness of the segments84, 85 touching one another at line 82 as in FIG. 10B unless an adjacentsegment 85 is forced up, as illustrated in FIG. 10A. Now the non-linearnature of the spring assembly is revealed, as best shown in FIG. 10A. Inthe deflected configuration shown in FIG. 10A, when one segment 85 ofthe spring 13 is forced upwards, only the thin portion 81 of the spring13 moves and relatively little force is required. In the nondeflectedconfiguration shown in FIG. 10B, showing the stiff or “hard” springconstant mode, if the left-hand side of the spring is constrained, itwill take a large force on the right side of the assembly to deflect orbend the spring down.

FIG. 11 illustrates several consecutive segments of the non-linearspring 13 illustrated in FIGS. 10A-10B. As illustrated, spring 13 isconnected to magnetic rods 12A1, 12A2. Magnetic rod 12A1 and thecorresponding spring segment 84 is illustrated locked down to solenoid14A1, after the solenoid 14A1 has pulled down its correspondingpermanent magnet 12A1 by the small angle Φ, while the adjacent solenoid14A2 is positioned to attract the next spring segment 85 by the sameangle Φ and longitudinal distance D11. In some embodiments, it is alsopossible for both solenoids 14A1 and 14A2 to be energizedsimultaneously. When a magnetic rod 12 exerts a force on a correspondingsegment, the only spring assembly resistance comes from the bending ofthe thin member 81 of the spring assembly 13. The flexing of this thinportion 81 of the spring assembly 13 over the small angle Φ is one ofonly two mechanical sources of friction in the artificial heart, thesecond being the flexible walls, e.g., bellows. In some embodiments, theangle Φ is less than about 10 degrees, 5 degrees, 4 degrees, 3 degrees,2.5 degrees, 2 degrees, 1.5 degrees, 1 degree or less, or between about1.5 degrees and 2.5 degrees, or about 1.84 degrees. In some embodiments,the longitudinal distance D11 between a segment 84 locked to thecorresponding solenoid 14A1 and an adjacent unlocked segment is betweenabout 0.05-0.5 inches, such as between about 0.1 inches and about 0.3inches, between about 0.1 inches and about 0.2 inches, or about 0.125inches in some embodiments. Careful design allows long life and nofatigue failures since stresses can be readily held within the elasticlimits of the metal used. When the left segment 84 is restrained andforce is applied to the top of the adjacent segment 85 the “hard” springconstant of the spring assembly is revealed. The entire spring assembly13 is available to resist the applied force and deflection of theassembly 13 is negligible to the forces generated by this artificialheart's solenoids 14A1, 14A2.

Parqueted and pre-finished hard wood floors is an analogy to theaforementioned spring concept. The factory made wood segments ofparqueted floors are glued to a coarse but thin textile which keeps theoften tiny wood segments firmly in place while providing a suitablesurface for the flooring adhesive to bond to. Furthermore, similar tothe spring segments shown in the configuration of FIG. 10B on a levelsurface the “hard” spring analogy prevents gaps from appearing on thesurface of the installed floor. This technique permits rapid and preciseinstallation of multi and small segmented hardwood floors.

FIGS. 12A and 12B illustrate a top view and side view, respectively of anon-linear helical spring 13 as previously described, with coupledmagnetic rods 12. As illustrated in FIG. 12B, magnetic rods 12 may behoused therethrough within apertures 89 of the spring 13. Otherapertures 88 are present to receive magnets 12 therethrough from othersegments of the spring 13, to allow the spring 13 to advantageouslyassume a more fully compressed configuration.

FIG. 13 illustrates more details of the manner in which the solenoid 14attracts the magnet 12 of spring 13. The spring magnets 12 and thesolenoids 14 of the artificial heart comprise at least one magneticmaterial. The magnetic materials are placed in a generally magneticallyaligned relationship as described elsewhere herein, to magneticallyinteract and actuate the axially movable plate 10 to facilitate the flowof blood into and out of the artificial heart.

In some embodiments, the spring magnets 12 and/or the solenoids 14comprise a “hard” ferromagnetic material, which is also commonlyreferred to as a permanent magnet. A permanent magnet is characterizedas a material showing resistance to external demagnetizing forces oncebeing magnetized. That is, a high external magnetic field is required inorder to remove the residual magnetism of a permanent magnet. Stateddifferently, a permanent magnet has very high intrinsic coercivity,which is a measure of its resistance to demagnetization. A permanentmagnet possesses poles of opposite polarity. The poles are regions of amagnet (usually at the end of the magnets) where the external magneticfield is strongest. Relative to Earth's magnetic poles, if the magnet isfree to turn, one pole will point to the magnetic north pole of theEarth, and is thus called a north pole of the magnet, which is indicatedby N in the drawings or otherwise called an N-pole. The opposite pole iscalled a south pole of the magnet, which is indicated by S in thedrawings or otherwise called a S-pole.

According to physical laws, poles of like polarity (N-N or S-S) repeleach other with a magnetic force. Conversely, poles of unlike polarity(N-S or S-N) attract each other with a magnetic force. Thus, structuresincorporating permanent magnets will repel each other when like poles ofthe structures are oriented to face each other, and likewise attracteach other when opposite poles of the structures are oriented to faceeach other. The magnitude of the force of magnetic attraction orrepulsion depends on the strength of the magnets and the distancebetween the poles.

Examples of known permanent magnet materials include alloys ofNeodymium-Iron-Boron (NdFeB), alloys of Aluminum-Nickel-Cobalt (AlNiCo),and Samarium Cobalt (SmCo). An electromagnet (current flowing through acoil of wire) can be substituted for a permanent magnet; in certainembodiments the solenoid 14 comprises a relatively weak permanent magnet92 along with a relatively strong electromagnet facilitated by coilwires 94A, 94B.

While various magnets, such as the spring magnets 12 can be referred toherein as magnetic rods, it will be appreciated that the magnets caneach be configured in various ways and take various shapes, e.g.,cylindrical, square, rectangular, or other polygons. In addition todiscrete magnets, in some embodiments, bonded permanent magnets may alsobe used. Bonded magnets can be flexible or rigid, and consist ofpowdered NdFeB, Ferrite or SmCo permanent magnet materials bonded in aflexible or rigid substrate of e.g., silicone, rubber, nitrile,polyethylene, epoxy, polyvinyl chloride, or nylon. The forming of thebonded magnet can be achieved by extrusion, compression molding,injection molding, calendaring, or printing. Bonded magnets enableunique flexible designs, and durable high tolerance shapes that areotherwise difficult to achieve.

In some embodiments, the magnetic cores 91 of magnets 12 can bedesirably coated, plated, encapsulated, or deposited prior to placementwith a selected protective material 90. The protective material 90 isselected to provide a corrosion resistant and biocompatible interface,and can also be desirably selected to form a durable interface, toprovide longevity to the system component, and thereby provideresistance to structural fatigue and/or failure.

The protective material 90 can be selected among various types ofmaterials known to provide the desired biocompatibility, resistance tocorrosion, and durability. For example, the protective material 90 cancomprise titanium or ferrous material plated, deposited, or otherwisecoated upon the magnetic material 91. As another example, the protectivematerial 90 can comprise a parylene coating. As other examples, theprotective material 90 can comprise a silicone polymer, a non-toxicepoxy, a medical grade polyurethane, or a U.V. curable medical acrylicco-polymer. The protective material 90 may be made up of various layers,each contributing to the protective and/or biocompatibilitycharacteristics of the protective material.

In some embodiments, the magnet 12 has a brittle neodymium core 91protected by a thin ferrous magnetic enclosure 90. Once in contact withthe solenoid assembly 14 (e.g., by virtue of permanent magnetic core 92of the solenoid 14), the magnet 12 of the spring 13 retains its positionlocked to the solenoid after power is removed from the solenoid coil 14.Solenoid coil 14 is operably connected to coil wires 94A, 94B. When afirst polarity voltage, e.g., a positive voltage is applied to wire 94Aand a second opposing polarity voltage, e.g., a negative voltage isapplied to wire 94B, end X of the solenoid 14 will represent magneticnorth and end Y of the solenoid 14 will represent magnetic south. Themagnet 12 and corresponding segment of the spring 13 will then bepositioned such that it is magnetically attracted to the solenoid 14,and then reversibly locked via action of the magnetic core 92 (e.g., apermanent magnetic core) of the solenoid, and in turn moving theoperably connected movable plate 10 closer to the solenoid 14.

In a later sequence, the current pulse to the solenoid 14 is applied inopposite polarity, causing the permanent magnet to be repelled andseparated from the solenoid. For example, when the second opposingpolarity voltage, e.g., a negative voltage is applied to wire 94A andthe first voltage, e.g., a positive voltage is applied to wire 94A, endX of solenoid 14 will be magnetic south while end Y of solenoid will bemagnetic north, and the magnet 12 of the spring 13 will overcome themagnetic attractive force of the magnetic core 92 of the solenoid 14,and be repelled away from the solenoid 14, moving the moveable plate 10further away from the solenoid 14.

FIGS. 14A-14D illustrate another embodiment of an artificial heart 95.Artificial heart 95 is similar to artificial hearts 50, 70 havingvarious components as illustrated in FIGS. 4A-4B and FIGS. 7A-7B, somedifferences as illustrated in FIG. 14A being that spring assemblies arepositioned near both the cranial and caudal ends of the artificial heart95, and the solenoid assembly is positioned longitudinally therebetween,or in other words sandwiched in the middle of the two spring assemblies.Embodiments that include such a feature can advantageously allow forpush and pull strokes making the solenoid operation more powerful andefficient. As noted with respect to other embodiments, the artificialheart 95 includes an outer housing 5. Outer housing 5 includes one ormore sidewalls 51, as well as top plate 3 and bottom plate 19. However,unlike the embodiments illustrated and described in connection withFIGS. 4A-4B and 7A-7B, central plate 10 is fixed, while top plate 3and/or bottom plate 19 are movable along a generally longitudinally axisof the artificial heart 95, e.g., a cranial-caudal axis. The artificialheart could include a single spring on either side of the solenoid ring14, a single spring on a first side and a plurality of springs on asecond side of the solenoid ring 14, or a plurality of springs on bothsides of the solenoid ring 14, such as a pair of springs in double helixconfigurations as previously described.

FIG. 14A also illustrates atrial springs 13, 29 configured as a doublehelix. First atrial spring 13 is operably connected at a first, e.g.,cranial end via attachment point 27 to an atrial-facing surface of thetop plate 3, and operably connected at second, e.g., caudal end viaattachment point 25 to an atrial-facing surface of the solenoid ring 14.Second atrial spring 29 is operably connected at a first, e.g., cranialend via attachment point 26 to an atrial-facing surface of the top plate3, and operably connected at second, e.g., caudal end via attachmentpoint 11 to an atrial-facing surface of the solenoid ring 14. Aplurality of magnets 12 are operably attached to atrial springs 13, 29in a 1:1 or other ratio as previously discussed, the total number ofmagnets 12 corresponding in a 1:1 or other ratio to the number ofsolenoids within the solenoid ring 14.

Still referring to FIG. 14A, ventricular springs 31, 32 are alsoconfigured as a double helix. First ventricular spring 31 is operablyconnected at a first, e.g., cranial end via attachment point 33 to aventricular-facing surface of the solenoid ring 14, and operablyconnected at second, e.g., caudal end via attachment point 20 to aventricular-facing surface of the solenoid ring 14. Second ventricularspring 32 is operably connected at a first, e.g., cranial end viaattachment point 34 to a ventricular-facing surface of the solenoid ring14, and operably connected at second, e.g., caudal end via attachmentpoint 30 to a ventricular-facing surface of the solenoid ring 14. Aplurality of magnets 35 are operably attached to ventricular springs 31,32 in a 1:1 or other ratio as previously discussed, the total number ofmagnets 35 corresponding in a 1:1 or other ratio to the number ofsolenoids within the solenoid ring 14. In the embodiment shown, thereare a total of 16 magnets attached to atrial springs 13, 29, a total of16 magnets attached to ventricular springs 31, 32, and a total of 16corresponding solenoids 14, although other numbers as previouslydiscussed can also be used depending on the desired clinical result.

FIG. 14B is a cross-sectional view through line B-B of FIG. 14A lookingfrom a generally cranial to a generally caudal direction. The solenoidring 14 (housed radially in between sidewall 51 of outer housing 50 andouter atrial wall 21 and/or ventricular wall 23) contains a plurality ofsolenoids, such as 16 solenoids as shown. However, other embodimentscould include, for example, between about 2-64 solenoids, 4-32solenoids, or 8-24 solenoids for example. These solenoids are marked 1Athrough 8A and 1B through 8B as illustrated. As noted previously, thefirst atrial spring 13 is connected at a caudal end to the atrial-facingsurface of the solenoid ring 14 at position 25 and the second atrialspring 29 is connected at a caudal end to the atrial-facing surface ofthe solenoid ring 14 at position 11. Also illustrated are solenoid coils28 as part of solenoid ring 14 within outer chamber 4, right atrium 6,left atrium 7, tricuspid valve 8, mitral valve 9, atrial septal wall 22and atrial outer wall 21.

FIG. 14C is a top view through line A-A of FIG. 14A looking from agenerally cranial to a generally caudal direction. Shown are an externalsurface of top plate 3, attachment points (in phantom) 26 and 27 ofrespective atrial springs 29 and 13, and openings within the top plate 3for ingress of blood into the artificial heart 95 from the superior venacava 1 and pulmonary vein 2. Inferior vena caval opening is not shown,and could be on the top plate 3, bottom plate 19, or sidewall 51.Alternatively, in some embodiments the superior vena cava could beanastomosed or otherwise attached to the inferior vena cava external tothe artificial heart 95 creating a common return conduit fordeoxygenated blood directly into the artificial heart 95.

With the axially moveable top wall 3 and bottom wall 19 of theartificial heart 95, in some embodiments it may be advantageous toanastomose one or more native vessels serving as a vascular conduit intoor out of the artificial heart 95 to a longitudinally flexible graftmaterial having bellows or accordion-like properties that is in turnoperably attached to the artificial heart 95, to reduce shear forces atthe attachment site of the vessels to the artificial heart 95.

FIG. 14D is a bottom view through line C-C of FIG. 14A looking up from agenerally caudal to cranial direction. Shown are an external surface ofbottom plate 19, attachment points (in phantom) 20, 30 of respectiveventricular springs 31, 32, and openings within the bottom plate 19 foregress of blood out of the artificial heart 95 across the aortic valve18 and pulmonic valve 17 and into the aorta 60 and pulmonary artery 61respectively.

FIGS. 15-16 are two-dimensional schematic incline plane representationsof the actual three-dimensional atrial helical springs 13, 29 andventricular helical springs 31, 32 and solenoid ring 14 as previouslyillustrated and described, at different points in the cardiac cycle. Asnoted previously, cranial end of the first atrial spring 13 is attachedto axially movable top plate 3 at attachment point 27, while the caudalend of the first atrial spring 13 is attached to the solenoid ring plate14 at attachment point 25. Cranial end of the second atrial spring 29 isattached to axially movable top plate 10 ant attachment point 26, whilethe caudal end of the second atrial spring 29 is attached to thesolenoid ring plate 14 at attachment point 11. Each atrial spring 13, 29is operably connected to a plurality of magnets (e.g., magnet rods 12connected to first spring 13, and magnet rods 12′ connected to secondspring 29) spaced apart along the length of the springs 13, 26, eachmagnet 12, 12′ corresponding to a particular solenoid 1A-8A or 1B-8Brespectively, such as in a 1:1 ratio.

Also as noted previously, first ventricular spring 31 is operablyconnected at a first, e.g., cranial end via attachment point 33 to aventricular-facing surface of the solenoid ring 14, and operablyconnected at second, e.g., caudal end via attachment point 20 to aventricular-facing surface of the solenoid ring 14. Second ventricularspring 32 is operably connected at a first, e.g., cranial end viaattachment point 34 to a ventricular-facing surface of the solenoid ring14, and operably connected at second, e.g., caudal end via attachmentpoint 30 to a ventricular-facing surface of the solenoid ring 14. Aplurality of magnets 35 are operably attached to ventricular springs 31,32 in a 1:1 or other ratio as previously discussed, the total number ofmagnets 35 corresponding in a 1:1 or other ratio to the number ofsolenoids within the solenoid ring 14. In some embodiments, theattachment points are spaced approximately 180 degrees apart along acircumference of a wall, plate, or other structure such that the forceis properly balanced.

At the start of the cardiac cycle, solenoids A1 and B1 are energizedsimultaneously. This unlocks the solenoid magnets 12, 12′ in the atrialhelical springs 13, 29 and pushes the top plate 3 away from the solenoidring 14, while pulling the magnets 35, 35′ on the ventricular helicalsprings 31, 32 in to lock on the associated solenoid magnets of A1-A8,B1-B8. The distance between the solenoid assembly 14 and the top plate 3thus increases step by step in a balanced and synchronized way. Thepower is then removed from the solenoids A1 and B1. The magnets 35, 35′on the ventricular side A1 and B1 are strong enough to hold in and lockinto the solenoid 14, and the magnets in atrium helical spring are farenough away from the solenoid to not relock on the A1 and B1 solenoids.Power is than applied to the A2 and B2 solenoids, this action continuesfor all the solenoids one pair at a time. This forces the bottom plate19 in a cranial direction, increasing the pressure in the ventricles 15and 16 closing the tricuspid value 8 and mitral valve 9 and ejectingblood out through the pulmonary valve 17 and aortic valve 18. FIG. 15illustrates the artificial heart at a point in the cardiac cyclefollowing ventricular contraction.

After the ventricular contraction is completed, reverse power is appliedto the solenoids starting on A8 and B8. This action will unlock themagnets 35, 35′ in ventricle helical springs 31, 32 associated with A8and B8 and then lock the magnets 12, 12′ in atrium helical springs 13,29 associated with A8 and B8, pushing the bottom plate 19 axially awayfrom solenoid coil assembly 14 and pulling the top plate 3 caudallytoward the solenoid assembly 14. The power is then removed from thesolenoids A8 and B8. The magnets 12, 12′ on the atrial side A1 and B1are strong enough to hold in lock and the magnets 35, 35′ in theventricular helical spring 31, 32 are far enough away from the solenoidto not relock on the A8, and B8 coils. Power is than applied to A7 andB7; these actions continue for all the solenoids one pair at a time.This forces the bottom plate 19 in a caudal direction, reduces thepressure in the ventricles 15 and 16 opens the tricuspid value 8 andmitral valve 9, thus allowing blood through to ventricles 15 and 16 andclose the pulmonary valve 17 and aortic valve 18. This completes thecardiac cycle, and the heart system then awaits the next cycle.

FIG. 17 illustrates more details of a “push-pull” solenoid assemblysimilar to that of FIG. 13, with features as described in connectionwith FIGS. 14A-16 above. Single atrial and ventricular springs areillustrated for simplicity. Once in contact with the solenoid assembly14 (e.g., by virtue of permanent magnetic core 92 of the solenoid 14),the magnet 12 of an atrial spring 13 retains its position locked to thesolenoid after power is removed from the solenoid coil 14. Solenoid coil14 is operably connected to coil wires 94A, 94B. When a first polarityvoltage, e.g., a positive voltage is applied to wire 94A and a secondopposing polarity voltage, e.g., a negative voltage is applied to wire94B, end X of the solenoid 14 will represent magnetic north and end Y ofthe solenoid 14 will represent magnetic south. The atrial spring magnet12 and corresponding segment of the atrial spring 13 will then bepositioned such that it is magnetically attracted to the solenoid 14,and then reversibly locked via action of the magnetic core 92 (e.g., apermanent magnetic core) of the solenoid, moving the top plate 3 closerto the solenoid 14. Conversely, the ventricular spring magnet 35 facingthe opposite pole of the solenoid 14, will be positioned such that it isrepelled from the solenoid 14, moving the bottom plate 19 away from thesolenoid 14.

In a later sequence, the current pulse to the solenoid 14 is applied inopposite polarity, causing the atrial spring magnet 12 to be repelledand separated from the solenoid 14. For example, when the secondopposing polarity voltage, e.g., a negative voltage is applied to wire94A and the first voltage, e.g., a positive voltage is applied to wire94A, end X of solenoid 14 will be magnetic south while end Y of solenoidwill be magnetic north, and the magnet 12 of the atrial spring 13 willovercome the magnetic attractive force of the magnetic core 92 of thesolenoid 14, and be repelled away from the solenoid 14, in turn movingthe top plate 3 away from the solenoid 14. Conversely, the ventricularspring magnet 35 facing the opposite pole of the solenoid 14, will bepositioned such that it is magnetically attracted to the solenoid 14,moving the bottom plate 19 closer toward the solenoid 14.

Disclosed herein are additional embodiments of an artificial heart. Someembodiments can be less than about 80%, 70%, 60%, 50%, 40%, 30%, or lessin size (e.g., one, two, or more dimensions) than embodiments disclosedabove. The heart can share a pumping mechanism for both ventricularchambers, and as such allows for a very compact size profile for theartificial heart. The heart valves can be sufficiently large to allowincreased, less turbulent blood flow. In some embodiments, thecross-sectional area of one or more of the valves is at least about 10%,15%, 20%, 25%, 30%, 35%, 40%, or more with respect to thecross-sectional area of the artificial heart 1800 at that givencross-section. The artificial heart can include a housing, a pluralityof opposing bellows springs, and a movable magnet module operablyattached to the bellows springs. In some embodiments, the bellows springand the magnet module are the only moving parts of the entire artificialheart system.

FIG. 18 illustrates an artificial heart 1800 according to someembodiments of the invention, including a plurality of chambers 806, 809(e.g., a right ventricle 815, and a left ventricle 831) contained withina housing of any appropriate shape, such as a cylindrical structure 811in some embodiments. Also shown in FIG. 18 are four valves 803, 804,827, and 828 (e.g., tricuspid valve 803, pulmonic valve 804, mitralvalve 827, and aortic valve 828). Vessels including the pulmonary vein,aorta, pulmonary artery, and vena cava are not illustrated forsimplicity. In some embodiments, each of the artificial heart's valvescan include a movable valve ring that reversibly contacts a fixed valveplate in order to create a valve seal. For example, the tricuspid valve803 can include a movable tricuspid valve ring 806 that reversiblycontacts the tricuspid valve plate 809. The pulmonic valve 804 caninclude a movable pulmonic valve ring 833 that reversibly contacts thepulmonic valve plate 832. The mitral valve 827 can include a movablemitral valve ring 826 that reversibly contacts the mitral valve plate825. The aortic valve 828 can include a movable aortic valve ring 829that reversibly contact the aortic valve plate 830. In some embodiments,one, two, or more of the valves can include helical springs operablyconnected to bellows springs, which are in turn operably attached to themoveable valve ring to advantageously facilitate gentle minimal forceclosure of the valve, as described in Applicant's co-pending U.S. patentapplication Ser. No. 14/603,101 entitled “Gentle Artificial Heart Valvewith Improved Wear Characteristics” filed on Jan. 22, 2015, and herebyincorporated by reference in its entirety.

In some embodiments, the artificial heart 1800 has common right and leftatrio-ventricular cavities. In some embodiments as illustrated in FIG.18, the artificial heart 1800 can have discrete atrial chambers such asthe right atrium 807 and left atrium 824, each having at least onemovable wall operably connected to an atrial bellows spring 823, 808operably connected to a respective atrial helical spring 822, 810. Theatrium 807, 824 allow for continuous blood inflow with pressure control.Filling of the atrium 807, 824 with blood can cause movement of theatrial helical spring 822, 810 to increase intraatrial pressure andcause the respective tricuspid valve 803 and the mitral valve 827 toopen, moving blood from the atria into the ventricles.

Still referring to FIG. 18, a magnet 818 can reside in a relativelycentral location of the artificial heart 1800, and be operably connectedto movable heart plate structure 817, which can be configured to act asthe cardiac “pump”. The magnet 818 could include both substantiallyhorizontal and vertical magnetic elements as illustrated in someembodiments, and north and south poles N, S as illustrated, and can bean electromagnet (or permanent magnet in other embodiments). The magnet818 can be moved in a first direction or a second direction apredetermined distance opposite the first direction via opposing poweredsolenoids, or coils 813, 821. The magnet 818 can be operably connectedon each side to right bellows 819 and left bellows 812 respectively, thebellows 819, 812 defining at least two respective chambers 815, 831.Each of the right bellows 819 and the left bellows 812 can includespring elements, and/or be each operably connected to one or morerespective helical springs, e.g., right helical spring 814 and lefthelical spring 820 also configured to assist the magnet 818 to move atthe start of heart motion and stop moving at the end of heart motion ofeach cardiac cycle. In some embodiments, the blood flow path candirectly or indirectly contact the solenoids in order to cool thesolenoids.

Also illustrated in FIG. 18 are fixed valve plates, including pulmonaryvalve plate 832 and aortic valve plate 830, which are operably connectedto one of the ends of their respective bellows 819, 812. Furtherillustrated are one or more sensors, such as position and/or speedsensors 816 configured to determine the position, speed, and/or otherparameters of the movable magnet 818 within the artificial heart 1800,described further below.

FIG. 18AA illustrates schematically an embodiment of a position sensingmodule 900 configured to detect the position or other parameters of themagnet within the artificial heart 1800 as previously described. In someembodiments, the module 900 can include a fixed, stationary component916 that can be mounted to the housing of the artificial heart 1800,such as at the inner wall. The module 900, e.g., the stationarycomponent 916 can include a laser 902 configured to project a laser beam918 through focus lens 904, collimator 906, and then mirror 908, whichallows the laser beam 918 to reflect at an angle, such as a right angleas shown. The laser beam 918 can then travel through position markerscreen 910 to laser detector 914. The module 900 can also include amovable portion that includes a position marker plate 912 operablymounted to the magnet and configured to move along with the magnet 18.As such, the laser source 902 can initially project the laser beam 918in a first direction, such as substantially parallel to the longitudinalaxis of the position marker plate 912 in some embodiments, and themirror 908 can reflect the laser beam 918 in a second direction. In someembodiments, the second direction is transverse to the longitudinal axisof the position marker plate 912 as shown. Such embodiments can beadvantageous in some cases to ensure that the laser source 902 and thelaser sensor 914 are in sufficient proximity to properly function.

FIGS. 18A and 18B schematically illustrate end views of the right heartand left heart respectively. FIG. 18A illustrates various artificialright heart structures including the tricuspid valve 803, pulmonic valve804, a first control circuit 801 and hardware 802. FIG. 18B illustratesvarious artificial left heart structures including the mitral valve 827,aortic valve 828, a second control circuit 834, and hardware 802.

In some embodiments, a cardiac cycle of an embodiment of an artificialheart can be described as follows, and illustrated schematically in FIG.19. At the start of the operation right coil 813 and left coil 821 aresupplied power, and a servomechanism keeps magnet 818 in Position 1 asshown (and illustrated in greater detail in FIG. 19H), where themagnetic tracking force on the right coil 813 is equal or substantiallyequal to the combined force of the spring force of the bellows 819, 812and/or the helical springs 820, 814; the artificial heart system 1800 isat rest. Prior to activation of the servomechanism system, the magnetpower may control the position, and lock the magnet to one side or theother. Once the servomechanism is activated, the magnet 818 can move toa predetermined position. In some embodiments, the predeterminedposition in preset by the servomechanism software and/or hardware, andmay be, for example, a minimum of about 0.10 inches, 0.05 inches, or0.01 inches from the locked position. Since the servomechanism caninclude a phase lock system, the servomechanism position can be absolutedepending on a servomechanism gain system. The position can be selectedto avoid certain components directly touching each other when theservomechanism is active (except in some embodiments at the start whenpower is off). Temperature, manufacturing tolerances, and othervariables can be taken into account to avoid servomechanism overshootingand other variables.

The heart cycle then begins as power is applied to coils 813, 821, tomove the magnet in Direction 1 illustrated by the arrow. Right and leftbellows springs 819, 812 as well as right and left helical springs 814,820 respectively assist in providing a pushing or pulling force to movemagnet 818 in Direction 1 with the force stored in the bellows springs819, 812 and helical springs 814, 820. When the magnet 818 is moved inDirection 1, deoxygenated blood moves into right heart chamber 806 fromthe vena cava and oxygenated blood moves out of left heart chamber 809into the aorta. As magnet 818 moves, its, speed, direction, and locationcan be sensed via one or more optical or non-optical sensors 816configured to detect the speed, direction, and/or location of the magnet808. The sensors 816 can be three-channel high-resolution sensors insome embodiments. The magnet 818 can move according to a predeterminedprofile set configured to preset the speed, direction of movement, andlocation of the magnet 818. The servomechanism (not shown) can be a highgain, phase lock, digital feedback system in some embodiments. Themagnet 818 can move according to the pre-programmed speed stored, forexample, in a memory and configured to position the magnet 808 withinthe heart 1800 within, for example, a tolerance of about 50 micrometers,or within about 0.01, 0.005, or 0.002 inches in some embodiments. Theservomechanism controlling the electromagnetic forces, in combinationwith feedback from the sensors and/or customizing the spring constantsof the helical springs, can be advantageously precisely configured suchthat various parts, do not physically contact each other even duringsystole or valve closure, preventing associated component wear. Forexample, the movable heart plate structure 817, when in use in someembodiments may not actually touch the surface of the correspondingaortic valve plate 830 or the pulmonary valve plate 832, but rather arein substantially close proximity to each other to effectuate functionalvalve closure. For example, two valve surfaces can rather come within,for example, within about 0.5, 0.4, 0.3, 0.2, 0.1, 0.09, 0.08, 0.07,0.06, 0.05, 0.04, 0.03, 0.02, 0.01 inches, or less of each other, e.g.,to close the valve without actually touching, which advantageouslyeliminates or substantially eliminates friction and component wear, andresults in a very long operating life compared with conventionalartificial hearts. Other embodiments as also disclosed herein can beconfigured such that no physical contact between valve surfaces occurs.

The forces supplied to magnet 818 to move in Direction 1 at the startare provided by coil 813, bellows springs 819, 812, and/or helicalsprings 814, 820. As the magnet moves to the center (e.g., Position 2,and illustrated in greater detail in FIG. 19B), the net force providedby bellows springs 819, 812 and helical springs 814, 820 are reduced toalmost zero, e.g., equal in the opposite direction. The driving forceprovided by powered coils 813, 821 is also reduced as the efficiency ofthe driving force decreases as the magnet approaches Position 2. Thekinetic energy within the magnet 818 keeps the magnet 818 moving pastthe midline of Position 2 in Direction 1 toward Position 3 (andillustrated in greater detail in FIG. 19C). As magnet 808 moves closerto Position 3, the bellows springs 819, 812, and/or helical springs 814,820 start to slow down the movement of the magnet 818 and energy isstored in the bellows springs 819, 812, and/or helical springs 814, 820.Coil 821 supplies the most energy to move magnet 808 toward Position 3as it becomes the most efficient at its proximity. When the magnet 818reaches Position 3 (where the combined spring forces equal the magneticattraction force), the sensors 813 will recognize the pre-programmedposition, and the system will reverse the drive direction, moving magnetin Direction 2 opposite of Direction 1. Aortic valve 828 will beconfigured to close, and mitral valve 827 will open allowing the bloodto enter the left heart chamber 809 and the blood in right heart chamber806 is forced out through the pulmonary valve 804 into the pulmonaryartery (not shown). The tricuspid valve 803 will then be configured toclose. The operation of magnet 818 moving in Direction 2 follows thesame pattern as described above, but in reverse, back toward Position 2(and illustrated in greater detail in FIG. 19D). When sensor 816 sensesthat magnet 818 reaches Position 1, the servomechanism controller willhold the magnet 818 in Position 1 (concluding the heart cycle) until thenext heart cycle begins. The servomechanism controller can have apreprogrammed heart rate, or respond to feedback from various internalor external inputs. The program can be stored in a memory. FIG. 19Eillustrates sectional views of an artificial heart 1800 with magnet incenter Position 2. FIG. 19F illustrates a cross-sectional view throughline X-X in the direction of arrows. FIG. 19G illustrates across-sectional view through line Y-Y in the direction of arrows.

The power drives on the coils can be switching regulated high-voltagedrive coils in some embodiments to increase efficiency. The power can besufficient to drive the artificial heart when the magnet is in thecenter position. An oscillation motion in the coils provided in thecontroller program can allow the system to recover. In operation,kinetic energy stored in the magnet itself is sufficient to move themagnet in a desired direction through the center position withoutstopping. The operation of the coils can be pre-programmed to provideefficiency.

FIG. 19H is a graph illustrating magnetic position (as illustrated inFIG. 19) with respect to various forces on the magnet as the magnettravels bi-directionally toward Direction 1 and Direction 2 oppositeDirection 1. As shown, at Position 1, the start of the heart cycle, thespring forces are equal to the magnetic attraction force. At Position 2,the central position of the magnet, the spring force and the magneticattraction forces are both zero. At Position 3, the end of the magnettravel, the magnetic attraction force is equal to the spring force. Asillustrated, the sum of the spring forces can be generally linear asshown, while the sum of the magnetic attraction forces can take theshape of two halves of parabolic curves as shown.

FIG. 19I illustrates an embodiment of functionality of a multi-channellocation, direction, and speed sensor configured to be in operativecommunication with a controller, such as a 3 channel location,direction, and speed sensor. The sensor can optionally include abidirectional counter, such as an up-down counter. In some embodiments,a control processor can be configured to amplify the sensor signal,and/or perform a counting function. As illustrated, each channel hasfirst “up” states and second “down” states. As illustrated, Channel Brises as A is in the “up” state, as the magnet 18 moves toward Position1, and the bidirectional counter is counting “up”. Channel B rises asChannel A is in the “down” state, as the magnet moves toward Position 3,and the bidirectional counter is counting “down”. The “up” and “down”counter is utilized to determine the location of the magnet 18. The rateor frequency of the count will translate into the speed of the movingmagnet 18. Channel C changes at the center Position 2, in the locationshown; and resets the bidirectional counter in the center position. IfChannel C is in the “down” position, the magnet 818 is relatively closerto Position 1 than Position 3. If Channel C is in the “up” position, themagnet 818 is relatively closer to Position 3 than Position 1. In someembodiments, the controller can be configured to receive data from oneor more physiologic sensors that can determine blood pressure, bloodoxygen level, temperature, hemoglobin level, or other parameters fromblood flowing through the artificial heart, and adjust operation of theheart to better optimize efficiency.

The bellows springs and/or helical springs can provide high efficiencyin some embodiments. If a spring is compressed to a distance X with aforce F, the energy stored in the spring E can be equal to the productof F and X. This stored energy can be released from the magnet withminimal loss regardless of the velocity of the traveling magnet, or thetime of each cycle. The solenoids can be at their most efficientpositions to convert electric energy when the coils are in closeproximity to the moving magnet. FIG. 20 illustrates a graphicalrelationship of solenoid force (in Newtons) on the Y axis with respectto stroke distance (measured in millimeters) in an embodiment of anartificial heart 1800, according to some embodiments of the invention.

In some embodiments, the atrial volume and ventricular volume are sharedwithin each respective chamber; atrial volume can increase, andventricular volume can decrease in a 1:1 correlation to the atrialvolume increase upon movement of the magnet in an appropriate direction,and vice versa. In some embodiments, the left and right heart pumpingelements are also shared. However, in some embodiments the artificialheart 1800 can include discrete atria as illustrated. The heart and/orany of its components can be made, for example, of a biocompatiblematerial, such as a metal, such as titanium or an alloy thereof,including SuperFlex titanium metal that has advantageous memory as wellas an extended flexing range.

Various other modifications, adaptations, and alternative designs are ofcourse possible in light of the above teachings. Therefore, it should beunderstood at this time that within the scope of the appended claims theinvention may be practiced otherwise than as specifically describedherein. It is contemplated that various combinations or subcombinationsof the specific features and aspects of the embodiments disclosed abovemay be made and still fall within one or more of the inventions.Further, the disclosure herein of any particular feature, aspect,method, property, characteristic, quality, attribute, element, or thelike in connection with an embodiment can be used in all otherembodiments set forth herein. Accordingly, it should be understood thatvarious features and aspects of the disclosed embodiments can becombined with or substituted for one another in order to form varyingmodes of the disclosed inventions. Thus, it is intended that the scopeof the present inventions herein disclosed should not be limited by theparticular disclosed embodiments described above. Moreover, while theinvention is susceptible to various modifications, and alternativeforms, specific examples thereof have been shown in the drawings and areherein described in detail. It should be understood, however, that theinvention is not to be limited to the particular forms or methodsdisclosed, but to the contrary, the invention is to cover allmodifications, equivalents, and alternatives falling within the spiritand scope of the various embodiments described and the appended claims.Any methods disclosed herein need not be performed in the order recited.The methods disclosed herein include certain actions taken by apractitioner; however, they can also include any third-party instructionof those actions, either expressly or by implication. For example,actions such as “attaching an artificial valve to a native valveannulus” includes “instructing the attaching of an artificial valve to anative valve annulus.” The ranges disclosed herein also encompass anyand all overlap, sub-ranges, and combinations thereof. Language such as“up to,” “at least,” “greater than,” “less than,” “between,” and thelike includes the number recited. Numbers preceded by a term such as“approximately”, “about”, and “substantially” as used herein include therecited numbers (e.g., about 10%=10%), and also represent an amountclose to the stated amount that still performs a desired function orachieves a desired result. For example, the terms “approximately”,“about”, and “substantially” may refer to an amount that is within lessthan 10% of, within less than 5% of, within less than 1% of, within lessthan 0.1% of, and within less than 0.01% of the stated amount.

What is claimed is:
 1. An artificial heart, comprising: an outer housingcomprising a right heart valve plate and a left heart valve plate spacedaxially apart by a first bellows spring and a second bellows spring; asolenoid connected to a first drive coil and a second drive coil, thefirst drive coil operably connected to the right heart valve plate andthe second drive coil operably connected to the left heart valve plate;a magnet operably connected to a plate structure spaced axially betweenthe first drive coil and the second drive coil, the magnet operablyconnected to a first end of the first bellows spring and a first end ofthe second bellows spring, the magnet configured to move axially uponactivation of the first drive coil and the second drive coil resultingin conversion of electrical energy to mechanical energy, thereby axiallyelongating one of the first bellows spring and the second bellows springand simultaneously contracting the other of the first bellows spring andthe second bellows spring resulting in the release of energy, movingblood in or out of the artificial heart by movement of the platestructure; at least one sensor configured to determine at least one ofthe position, velocity, and direction of travel of the magnet; and aservomechanism controller configured to receive data from the sensor andcontrol power to the first drive coil and the second drive coil, therebyactuating the magnet and the plate structure.
 2. The artificial heart ofclaim 1, wherein the servomechanism controller is configured to provideprecise control of a position and speed of the magnet at all times. 3.The artificial heart of claim 1, wherein the solenoid is configured toactuate the magnet.
 4. The artificial heart of claim 1, wherein theartificial heart comprises biocompatible titanium.
 5. The artificialheart of claim 1, wherein the outer housing is rigid.
 6. The artificialheart of claim 1, wherein the controller comprises a high gain, phaselock digital servomechanism feedback system.
 7. The artificial heart ofclaim 1, wherein the controller is configured such that the platestructure never physically touches the left heart valve plate or theright heart valve plate during normal operation, thus increasingoperating life.
 8. The artificial heart of claim 7, wherein thecontroller is configured to receive data from the at least one sensorregarding at least one of blood pressure, blood oxygen level, and bloodtemperature, analyze the data, and adjust power to the first drive coiland the second drive coil accordingly.
 9. The artificial heart of claim1, wherein the artificial heart is configured such that the platestructure can move to within about 0.01 inches of the left heart valveplate or the right heart valve plate without actually contacting theleft heart valve plate or the right heart valve plate during normaloperation.
 10. The artificial heart of claim 1, wherein the outerhousing comprises discrete left and right atrial chambers.
 11. Theartificial heart of claim 10, wherein the discrete left and right atrialchambers are configured to control pressure and range of operation. 12.The artificial heart of claim 1, wherein the artificial heart isconfigured such that blood flow through the artificial heart directlycools the solenoid.
 13. The artificial heart of claim 1, wherein the atleast one sensor is configured to determine at least one of bloodpressure, blood oxygen level, and blood temperature.
 14. The artificialheart of claim 1, wherein each of the first and second drive coils,right and left heart valve plates, and at least one sensor are partsmounted to the artificial heart, wherein the artificial heart does notcomprises any loose wires or sensors, and wherein the artificial heartis configured to minimize force on the parts when the artificial heartis pumping.